"YOUR_USERNAME" is any way you uniquely identify your users, and "3600" is the number of seconds in which the ticket will expire.

If you don't yet have an app key and secret from Sinch, you can get them for free here: www.sinch.com/signup.

Once you've successfully generated the ticket, you can use it to securely start the Sinch client. Follow any of our client-side JavaScript tutorials to use the Sinch client to make phone calls and send instant messages: